1. Field of the Invention
The present invention relates to a roll connector structure for a vehicle which reliably maintains an electric connection between a steering wheel and a vehicle body.
2. Description of the Related Art
Slip rings and roll connectors are known as members which reliably maintain electric connection between a steering wheel side and a vehicle body side. The slip ring has the merit that the manufacturing cost thereof is low because the structure is a simple structure in which a moving contact slides on a stationary contact. On the other hand, the slip ring has the disadvantage that the conductive state between the steering wheel side and the vehicle body side deteriorates due to the moving and stationary contacts being worn out in a case in which the slip ring is used over a long time. Therefore, as more and more vehicles have come to have air bag devices as a standard equipment, roll connectors have come to be used because the reliability of the roll connector is higher than that of the slip ring.
In FIG. 3, a conventional roll connector 100 and a steering wheel 102 are shown in order to explain a conventional method of connecting between the steering wheel and the vehicle body. As shown in FIG. 3, a horn switch (not shown in the drawing) and a cruise control switch 104, as well as an audio and telephone switch 106, which reflects an option that vehicle drivers have come to demand in recent years, are provided at the steering wheel 102. Wire harnesses (electric wires) 108 and 110 are pulled out from the cruise control switch 104 and the audio and telephone switch 106, respectively. The wire harnesses (electric wires) 108 and 110 are connected to connectors 114 and 116 which are provided in parallel the vicinity of a hub 112 of the steering wheel 102.
The roll connector 100 is fixed to a steering shaft (not shown in the drawing). The roll connector 100 is mounted at a position which is at the front side of the steering wheel 102. The roll connector 100 comprises a stator side casing 118, a rotor side casing 120, and a cable (not shown in the drawing). The stator side casing 118 has a substantially cylindrical configuration with a bottom. The rotor side casing 120 is mounted on the stator side casing 118 so as to be rotatable with respect to the stator side casing 118, and rotates integrally with the steering wheel 102. The cable is accommodated between the stator side casing 118 and the rotor side casing 120 and is wound in a spiral like manner. Connectors 122 and 124, which are connected to the connectors 114 and 116 provided at the steering wheel 102, are provided in parallel at the rotor side casing 120. Another connector 126, which is connected to an inflator of an electric ignition type air bag device, is provided at the rotor side casing 120, together with a wire harness 128.
As mentioned above, not only the horn switch and the cruise control switch 104 are provided at the steering wheel 102, but also various types of other switches, such as the audio and telephone switch 106 and/or a switch for a car navigation system, are provided at the steering wheel 102, which reflects manufacturers"" effort to address the recent trends of requirements of drivers. Accordingly, many problems arise, such as the wiring of the wire harnesses becomes complicated and complex in the wiring structure applied to the conventional roll connector 100, and it becomes difficult to obtain sufficient space for the wire harnesses 108 and 110 and space for the connectors 114 and 116.
The present invention takes the facts mentioned above into consideration, and an object of the present invention is to provide a roll connector structure for a vehicle in which there is no complicated or complex wiring in the steering wheel and the space within the steering wheel can be utilized efficiently.
In accordance with a first aspect of the present invention, there is provided a roll connector structure for a vehicle including a stator side casing which is fixed to a steering column, a rotor side casing which is mounted to the stator side casing and rotates integrally with a steering wheel, and a cable which is accommodated between the stator side casing and the rotor side casing in a state of being wound in a spiral manner, wherein at least one steering switch is connected to the rotor side casing without wiring.
In accordance with a second aspect of the present invention, there is provided a roll connector structure for a vehicle according to the first aspect, wherein the rotor side casing has at least one connector, and the at least one steering switch has a plug portion corresponding to the at least one connector.
In accordance with a third aspect of the present invention, there is provided a roll connector structure for a vehicle according to the first aspect, wherein one portion of the at least one steering switch is formed integrally with the rotor side casing, and other portion of the at least one steering switch is connected to the one portion of the at least one steering switch.
In accordance with a fourth aspect of the present invention, there is provided a roll connector structure for a vehicle including a stator side casing which is fixed to a steering column, a rotor side casing which is mounted to the stator side casing and rotates integrally with a steering wheel, and a cable which is accommodated between the stator side casing and the rotor side casing, wherein at least one steering switch is connected to the rotor side casing without wiring.
In accordance with the first and forth aspects of the present invention, As the steering wheel is rotated, the rotor side casing rotates, accompanying a rotation of the steering wheel, in the same direction as the steering wheel, with respect to the stator side casing. In the aspects, because at least one steering switch is connected to the rotor side casing without wiring, the wire harness(es) and the connector(s) for the steering switch(es) is (are) no needed. Accordingly, in the aspects, the number of wirings of the wire harnesses and the number of the connectors at the steering wheel side can be reduced compared to those in the conventional structure of the roll connector.